Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add personamanagmentlayer/pcl --skill analytical-databases-expertgit clone --depth 1 https://github.com/personamanagmentlayer/pclWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/personamanagmentlayer/pcl/analytical-databases-expert)<a href="https://agentmods.dev/skills/personamanagmentlayer/pcl/analytical-databases-expert"><img src="https://agentmods.dev/badge/skills/personamanagmentlayer/pcl/analytical-databases-expert.svg" alt="Measured on agentmods" height="20"></a>- NVIDIA SkillSpector pass
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00100 | $0.02487 |
| Opus 5 | $0.00050 | $0.01243 |
| Sonnet 5 | $0.00020 | $0.00497 |
| Haiku 4.5 | $0.00010 | $0.00249 |
Grade A, and why
analytical-databases-expert scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 274 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Analytical Databases Expert
Columnar engines answer aggregate questions over large tables. They are not faster row stores — they trade single-row access for the ability to scan one column of a billion rows without touching the rest.
Core Concepts
Why Columnar Wins
Storing values of one column contiguously means a query reads only the columns
it names, and values of one type compress together far better than mixed rows.
SELECT avg(amount) FROM events touches one column; the row store reads every
byte of every row.
The corollary is the cost: fetching one complete row means reassembling it from every column, and single-row updates are expensive or unsupported. Use a row store for transactions and a columnar store for analysis. Trying to make one system do both well is the usual architectural mistake.
The Data Is Often the Format
With Parquet, storage and engine are separable. Files on object storage, queried by whatever engine suits: DuckDB locally, Spark for scale, the warehouse for governed access. Choosing the format well matters more than choosing the engine.
Selection Is About Deployment, Not Speed
| Engine | Fits | Cost |
|---|---|---|
| DuckDB | Embedded analytics, notebooks, CI, single-node up to hundreds of GB | Single process; no concurrent writers |
| ClickHouse | High-ingest real-time analytics, dashboards over billions of rows | Operationally demanding; eventual-consistency semantics |
| Cloud warehouse | Governed shared access, elastic scale, SQL for everyone | Cost grows with carelessness; vendor coupling |
| Spark / lakehouse | Petabyte batch, heavy transformation, ML feature pipelines | Latency and complexity |
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2d ago First seen · 274 lines · 100 tokens per session scan A ac620a9ac1a2
analytical-databases-expert is a skill published in the GitHub repository personamanagmentlayer/pcl (40 stars, last pushed today), licensed Apache-2.0. It adds 100 tokens to every session and 2,487 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-05.
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